The main requirements of a wet shaving preparation are to maintain the beard in softened condition, to lubricate the passage of the razor over the face, and, it has been suggested, to support the beard hair for cutting. In addition, the preparation should not irritate the skin, should be easily rinsed from the razor and the face, should be stable over a range of temperatures, non-corrosive to the razor blade, and resistant to premature drying out and collapse.
Currently the most widely used form of shaving preparation is the type referred to herein as an instant foam, which is dispensed from a pressurized aerosol container in the form of a rich lather for spreading on the area to be shaved, which preferably has been washed and left wet to further help soften and prepare the beard. The essential ingredients of such a composition are water, a soap component, which may comprise anionic, cationic, amphoteric, or nonionic surfactants and permitted combinations thereof, and a propellant. The constituents of the soap component, as well as the other ingredients of the composition, are so selected, as is now well known in the art, such that an instant foam shave preparation having excellent performance attributes may readily be formulated. The same essential ingredients, appropriately selected and in appropriate concentrations, with or without the addition of a water-soluble polymer as a gelling agent, can be formulated to make a composition for a self-foaming gel (often called a "post-foaming gel" and the propellant referred to in this context as the "post-foaming agent"), a shave preparation product form that has achieved
For an extensive discussion of the formulation of shaving Preparations, including instant foams and self-foaming gels, reference may be made to Harry's Cosmeticology, J. B. Wilkinson and R. J. Moore, eds., 7th edition, Chemical Publishing Co., N.Y., 1982, pp. 156-175, which is herein fully incorporated by reference.
The two above-mentioned product forms, often referred to simply as foams and gels, together dominate the marketplace for wet shave preparations, the combined lather and brushless creams, soap sticks, and other product forms now accounting for only a fairly small share of market. It has been suggested among those preferring gels that this product form provides a smoother, closer, more comfortable shave, with fewer nicks and cuts. Devotees of foams tend to like having the product already foamed as it comes out of the can so that it doesn't have to be worked into a lather by spreading, plus easy spread and rinsing qualities, and the absence of the cold feel of a gel. Consequently there is a continuing effort to develop improved shaving preparations that would combine, in one product, the advantages associated with both the best foams and gels.